Updated, 8:41 a.m.:

In a unified rebuke of Mayor Vincent C. Gray’s fiscal priorities, all but one D.C. Council member has signed a letter telling the mayor they will not support his plan to spend a $42 million budget surplus.

The letter, orchestrated by D.C. Council Chairman Kwame Brown (D), says the city should keep the money in the bank until officials have a better picture of the city’s finances.

“We would like to give you and your staff...at least two months to continue your work to address these spending pressures,” the letter states. The only city lawmaker not to sign it was Ward 1 Council member Jim Graham (D).

The letter represents an escalation in the showdown between Gray and Brown over what to do with an unexpected windfall in the fiscal year 2012 budget.

Brown delivered the letter to Gray hours before the two set out for a joint trip to New Hampshire to press for D.C. statehood. When the men met at Baltimore-Washington International Marshall Airport Friday morning, they exchanged a brief handshake but otherwise did not speak.

The extra money was discovered because of higher-than-expected tax revenues. Brown wants to use it to shore up the city’s reserve account or carry it over to partially offset a predicted shortfall in the fiscal 2013 budget.

But in a Dec. 23 letter, Gray told Brown he wants the money to address some priorities in the current year’s budget, including a $21 million gap in the D.C. public schools budget.

By organizing his colleagues against the mayor, Brown is trying to position the council as being more fiscally responsible than the city’s chief executive. Chief Financial Officer Natwar M. Gandhi has made an initial estimate of a $106 million shortfall in fiscal 2013. But Gray administration officials are optimistic that city finances will continue to improve, and the mayor said Thursday he is trying to avoid having to make unnecessary mid-year budget cuts.

Gray said in a statement that he was “disappointed” by the council’s letter.

“Responsible fiscal management means taking decisive action to address [budget shortfalls] right away,” he said. “We look forward to working with the Council to resolve this matter quickly and to preserve the District’s strong fiscal position.”

A senior aide who spoke on the condition of anonymity said Thursday night that Gray had hoped to use the fiscal 2012 surplus to address as much as possible of the current-year shortfall before a trip next month to visit Wall Street bond raters.

Gray’s plan to spend the money, rather than save it, garnered particularly strong criticism from charter school advocates, who are upset that about half of the money would go to the D.C. Public Schools without an equivalent payment to charters.

Staff writer Mike DeBonis contributed to this report.